The present invention relates to a crankshaft assembly with a coated crank pin, and more particularly, to a crankshaft assembly with a coated crank pin used with a roller element bearing.
It is known for a motorcycle engine, and specifically a V-twin style engine, to include a crankshaft assembly including first and second flywheel halves coupled together with a single crank pin. The crank pin is connected to the flywheel halves in a variety of ways. One option is to extend threaded ends of the crank pin through holes in the opposed flywheel halves and to thread nuts onto the ends of the crank pins to secure the assembly together. Another method is to press-fit non-threaded ends of the crank pin into the holes of the opposed flywheel halves.
Sometimes, the press-fit can be strengthened by using a press-soldering process which creates a thin layer (approximately 5 μm) of solder between the press-fit components. Other methods of strengthening the press-fit connection include pressing a solid plug into a bore of the crank pin after it is press-fit into the holes of the flywheel halves, case hardening one or both of the press-fit components, or keying the press-fit.
In some assemblies, friction enhancers (e.g., platings or coatings) on the crank pin are used to enhance a press-fit connection for a crank pin on a crankshaft assembly. However, these enhancers were believed to be incompatible with roller element bearings resulting in an adverse effect on the performance of the roller element bearings. To overcome this perceived deficiency, masking of the bearing contact surface of the crank pin was introduced. However, masking is labor intensive and inefficient, and if masking is not done properly, bearing performance could be adversely impacted.